In a town suffering a plague of vermin, the council began offering money to anybody who could prove they had killed rats by bringing the corpses to a recording office. For a time, the scheme seemed successful, and the numbers of rats being brought in decreased. But then they began to rise again. Puzzled council officials followed the most successful rat-catchers — and discovered they were breeding rats specifically to kill for the cash.

Offering increased incentives is never as straightforward as it may seem. When the CIA instituted a programme to reward field agents according to how many spies they recruited, they found numbers went up, but quality went down. Civil servants judged on the results of training programmes they ran began to screen out those who most needed help.

And introducing three points for a win might have had a detrimental effect on football.

Falling crowds call for drastic measures

Two points for a win was a logical starting point for the league, and stems directly from the days of challenge matches. Two people or teams compete for a prize pot, the winner takes all, and the pot is split if there is a draw. That went on without challenge for more than 90 years, but by 1980, football was facing serious difficulties. Crowds had almost halved from a high of more than 40 million a season in the early 1950s, and it was clear that something had to be done. That October, the chairmen of every league club met in Solihull to set out a vision for the future.

"The recession has given a dwindling football public a stricter sense of priorities," wrote David Lacey in the Guardian. "Going to watch a soccer match comes lower down the list than might have been the case because of dull play, crowd violence, over-exposure on television, and the increased cost not only of admission but of getting to and from the ground and having something to eat or drink along the way. When cash is short, people are finding something better, and cheaper, to do."

Clubs were never going to turn down television money, and as the boom of the 1990s demonstrated, it is far from clear that more football on television leads to fewer fans in the ground. They didn't have the resources properly to tackle hooliganism - it was the sport's great good fortune that the periods during which the recommendations of the Taylor Report had to be implemented coincided both with Sky's investment and with a period of general prosperity - and they could do little about the economy.

But they could tackle "dull play" – and there was plenty of that.

This, after all, was only a month after the Stoke City manager, Alan Durban, had advised journalists critical of his tactics in a glum 0-0 draw at Arsenal that if they wanted entertainment, they should go and watch clowns. So a working party under Jimmy Hill proposed increasing the reward for victory to three points. Most accepted the logic of his argument without demur, although there was the odd dissenting voice.

"It could make a team a goal up want to sit on their lead that bit more than at present," suggested the Arsenal manager, Terry Neill.

Champions will always be champions

So what difference did it make? In one sense, none at all. Apply three points for a win to every season going back to the second world war, and in each case the champions remain the same. Apply two points for a win to each season since the amendment, and only in 1994-95 would it have changed things, handing Manchester United the title on goal-difference ahead of Blackburn (and even then, only because Blackburn conceded a very late free-kick to Jamie Redknapp in their final game, away to Liverpool).

It could be argued, though, that that is a sign of strength: under three points for a win, as under two points for a win, the best team prevails. In other ways, the change can be seen as having had limited success. In the five seasons before the switch, there were an average of 133.0 draws per season in what was then the First Division; in the five seasons after, there was an average of 113.4. By way of comparison, there were 100 in the Premier League last season and if you extrapolate that to take account of the reduction in the number of top-flight teams from 22 to 20, you get a figure of 121.6.

A further incentive for winning

So it seems that after 1981 teams became more concerned with winning, and that there has been a back-sliding since. Fifa, apparently worried by how a US audience would deal with draws, instituted three points for a win ahead of the 1994 World Cup. It made no difference, 36 group games producing eight draws, just as they had at Italia 90.

The change seems also to have promoted more attacking play. In the five seasons leading up to it, home teams averaged 1.60 goals per game and away teams 1.01; afterwards home teams averaged 1.64 and away teams 1.07. (Last season the figures were 1.53 and 1.11). That is a small change, but optimists could even argue that away teams had become proportionally more attacking – suggesting they were less prepared to play for draws.

Other factors in the goal glut

Still, it would be difficult to claim, as Hill repeatedly has, that three points for a win revolutionised the game. It could be noted, for instance, that in 1980-81, the last season of two points for a win, the number of draws had already fallen to 118, while average goals per game stood at 1.64 for home teams and 1.02 for away: perhaps the trend was already in that direction. Certainly the outlawing of the back-pass and the tackle from behind made a far more radical impact. Goals per game shot up from 2.31 in Italia 90 to 2.71 at USA 94.

Was Terry Neill right?

More worrying figures emerge from a 2005 study by the economists Luis Garicano and Ignacio Palacios-Huerta into the impact of the move from two points for a win to three made in Spain. Fifa made three points for a win part of its Laws of the Game in 1995, and they were adopted worldwide ahead of the 1995-96 season.

In their paper Sabotage in Tournaments: Making the Beautiful Game a Bit Less Beautiful, Garicano and Palacios-Huerta analysed the 1994-95 season – the last of two points for a win – and compared it to the 1998-99 season, choosing the fourth season of the new protocol because "it does not require us to assume that teams were able to immediately adjust their behaviour to the new situation". They also used matches in the Copa del Rey – which retained the same knockout structure – as a control against other agents of interference – tactical developments, stricter refereeing and the like.

Their study is too complex to discuss in much detail here – and their easy categorisations of certain players as "attacking" or "defensive" seems over-simplistic – but certain points stand out. Essentially, Neill's concern was borne out: the study found that "when ahead, teams became more conservative, increasing their defenders, scoring less goals, and allowing fewer attempts to score by their opponents".

As might be expected "the introduction of the new incentives was followed by a decrease in the number of ties". The corollary to that, though, was that "the number of matches decided by a large number of goals declined. Measures of offensive effort such as shot attempts on goal and corner kicks increased while indicators of sabotage activity such as fouls and unsporting behaviour punished with yellow cards also increased."

More precisely "attacking effort" increased by around 10 per cent (factoring in any external changes revealed by the Copa del Rey), while fouls went up by 12.5 per cent. "The net result of these opposing forces is that the number of goals scored did not change". In other words, sides were more desperate to go ahead, but having done so, became more negative, because they now stood to lose two points rather than just one by conceding.

The trailing team, meanwhile, still fights for only one point, and that point is proportionally worth less under three points for a win (although an equaliser, of course, is a necessary step on the way to three points). Garicano and Palacios-Huerta show that under three points for a win "the probability of scoring an additional goal by a team that is ahead significantly drops; moreover, by the end of the match, the losing teams ends up making significantly fewer attempts on goal than before the incentive change."

Dirty teams mean fewer fans

Given that games in which the lead changes hands tend to be the most gripping, that sounds like bad news for football, even if the intensity of the game – as shown by the growing number of fouls - increases. The figures bear that out. "We find that attendances at any given stadium significantly decreases when being visited by teams that play dirtier," said Garicano and Palacios-Huerta. Their figures demonstrate a team protecting a lead is significantly dirtier under three points for a win than under two.

In other words, and when all else is accounted for, three points for a win seems to have had a detrimental effect.

The benefits

And yet what is the alternative? Herbert Chapman had warned of the dangers of placing too great an emphasis on victory half a century earlier. Developing the W-M at Arsenal, he was heavily criticised for making the game more pragmatic, stripping it of some of its traditional aesthetic qualities, something he seemed to regret in a series of writings published shortly after his death in 1934.

"It is no longer necessary for a team to play well," he said. "They must get goals, no matter how, and the points. The measure of their skill is, in fact, judged by their position in the League table."

Which, most would agree, is as it should be: nobody wants games decided by a panel of judges giving points for artistic merit.

Three points for a win at least helps prevent teams coming to a tacit agreement and playing out the final minutes of games for a draw. The question is, is it worth the cost?